This was originally posted as Shapeoko: Part 6, because I apparently can’t count.
A while ago I ordered a 300W ER-11 DC spindle kit from China to install in my Shapeoko. I finally got to the post office yesterday (stupid recipient-must-be-present shipping) to pick it up, am impressed with the whole process. Most of this post is about the spindle, there is some more belt tensioner tinkering down at the bottom.
Since I’m in the habit of posting about classes I take at the beginning and end of the semester, and often find something interesting when I look at them later, some quick impressions for courses I’m involved in for the Spring 2013 semester.
Teaching: CS275: Discrete Mathematics
I did this last semester, but under a different primary instructor. I again have pretty much free reign over the recitation period for an hour a week, but this time I do get to do a little bit of new material instead of just examples, and the suggestions on this I should cover are shorter and less specific. I’m more comfortable with the material having done it recently, and my classes seem a little more lively, so it should be a little more fun this time around. That said, doing the same lesson twice back-to-back is slightly more demanding than with a gap, and it is very easy to forget what you did with each group. I’m balancing being a little less organized in the first section with tending to run out of time in the 2nd, so I think they’re getting similar coverage, although the second section is probably having more fun.
Taking: GS650: Preparing Future Faculty
This is a two credit hour, once a week evening course for graduate students who think they might end up in academia. I’m building up a pile of technology-related degrees, have a deep well of contempt for the tech industry, and like teaching, so that sounds right. It actually seems like it will be more useful to me than I expected, in addition to being mostly composed of reading the appropriate news streams, listening to experts talk, and reflecting on both, which is basically what I do with myself anyway.
Taking: LIN511: Introduction to Computational Linguistics
I can talk about how I’m taking this because I thought it would be good for me to look at the other kind of language tools, and how my interest in the cognitive science aspects of computer systems covers it, but I’m really just taking it because it sounded interesting, no one told me I couldn’t (and in fact all the appropriate people encouraged it), and why else have I ever done anything, ever? There is one other CS student in there, and about 34 mixed graduate and undergraduate linguistics students, so my perspective is certainly the minority perspective, although the instructor came to linguistics from computing (and is hilariously British). I came in expecting to need to self-teach a lot of linguistics material, but talking to my classmates, they seem to be having to work as much on the linguistics aspects as I am, and having trouble with the computer parts, so I guess I’m ahead? So far the bulk of the assigned material has been structured manipulation of character srings (Using DATR, which is basically a generic string class system implemented in an ancient dialect of Prolog…), which is for me mostly a good exercise in remembering the OO way that many CS folks view the world. It is interesting, and I’m not suffering, so we’ll call committing to this whim a good choice.
I’m also still not rid of my MS project. I’m deeply tired of it at this point. I’m working to arrange the thing I would like to be working on as a PhD while I continue to try to clear out the parts of the MS project that have never worked, hopefully it will be reasonably fast and graceful.
I’ve been watching the talks out of 29c3 as they become available online for the last couple days, and these are my favorites with comments. I’ve never come up with an excuse to actually go, but always find that it is the conference with the most things I am excited about every year, and end up watching more recorded sessions than I could have attended had I been present. The ones I picked below were both topics I found interesting and good presentations – there were a couple I hoped would be good but had talks that made me just give up and read the paper that I won’t mention here.
The breakage of permissions under recent PolKit/logind is flabbergasting. They have completely subverted UNIX groups/permissions in a difficult-to-unbreak way. And I get cheerful little update messages saying things like “You no longer need to be in the camera group to use cameras” like it’s a fucking feature (and they’re lying; they mean users logged in locally no longer need to be in the camera group – remote users still need it). If I want a user to have access to some hardware on a machine, I’ll give it permissions. If I don’t, I probably don’t for a reason. Let’s talk use cases: perhaps you would like to hide the camera from a kid’s user. Or you would like to check on something with the camera attached to your remote machine. Or work a music player via SSH. Or generally use the resources on the machine you bothered to log into remotely because why the fuck else would you have logged in there? Every one of those is now more complicated to accomplish. Adding a facility to enable/disable permissions for remote or local users might be reasonable, but just fucking breaking groups for a couple use cases no one uses is moronic. (Seriously, Fast User Switching keeps coming up as a rationale for breaking things. Has anyone, ever used fast user switching on one of the platforms that supports it? There are usually more computer-like-devices than people in a household now, it isn’t relevant.)
Can someone please come up with a straightforward way to just noop all the PolKit bullshit so I can have my UNIX box back from the FreeDesktop assholes?
I got some more time to work on my Shapeoko over the last few days, and now have mostly correct 3-axis motion. As before, details under the fold.
I’ve made a habit of these posts after SC every year, and took the pictures, so away we go.
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Naturally, this post is a follow-on to Shapeoko: Part 1 and Shapeoko: Part 2. I’ve basically put the machine together now, and can move the X and Z axis around from the host computer, but still have to figure out belt attachments for the Y axis, and run the wiring in a sane way. I was holding up a microswitch to the various relevant spots for end-stops as I went, and everything but detecting the upper extreme of the Z axis should be easy. As in the last two posts, there is an assembly gallery under the fold.
This continues from where I left off in my previous post Shapeoko: Part 1.
I alternated my Sunday afternoon/evening between tackling my grading backlog and building pieces of the Shapeoko. This pattern works well for tapping since they are both exceptionally tedious tasks, but in different ways. Gallery with captions below the fold:
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My Shapeoko kit arrived from Inventables while I was away at SC.
I’ve been trying to build myself a small CNC milling machine since 2009, and contemplating it for longer than that. It became clear that my original design, however educational, was a dead end sometime last year. I’d been idly watching the Shapeoko project for some time as it had similar aspirations to my design, and a couple months ago I was in a particularly mechanical mood when I saw that a batch had reached enough buyers to be produced, so I bought in for a mechanical kit to mount my existing electronics on.
The Shapeoko community is really excellent, and the kit was designed to be flexible, so I’m starting off with some suggested modifications – I’m using NEMA23 motors instead of the usual NEMA17 on the X and Y axis, because I already had some nice Lin Engineering 130 oz-in NEMA23 motors and the frame can fit them. I’m configuring for dual Y motors, which give more even force across the Y axis, and routing my belts on the outside of the frame, since I needed to buy different hardware for the NEMA23 motors anyway and this particular modification is widely recommended.
There is a gallery to document my first round of assembly below the fold (captions don’t display properly in the RSS feed).
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I’ve got my pictures from the event up in an album in google’s cloud.
Here are the big, cool things I learned on the floor or at the various evening events:
There will be at least one more SC12 post later, when my cube of schwag arrives. The T-shirt harvest was great this year…
